1. Field of the Invention
The present invention relates generally to Anthropomorphic Test Devices (ATD) and, more particularly, to an omnidirectional neck assembly for an ATD that can be used to assess and predict injuries under crash, under body explosive, and aerospace ejection seat testing environments.
2. Description of the Related Art
Automotive, aviation, military, and other vehicle manufacturers conduct a wide variety of collision, ejection and under-body-blast (UBB) testing to measure the effects of an impact upon a vehicle and its occupants. Through the testing, a vehicle manufacturer gains valuable information that can be used to improve the impact worthiness of the vehicle.
Impact testing often involves the use of anthropomorphic test devices, better known as “crash test dummies.” During the testing, an operator places a crash test dummy inside a vehicle, and the vehicle undergoes a simulated collision, UBB, or ejection. The testing exposes the crash test dummy to high inertial loading, and sensors inside the crash test dummy, such as load cells, displacement sensors, accelerometers, pressure gauges, angle rate sensors, and the like, generate electrical signals of data corresponding to the loading. Cables or wires transmit these electrical signals of data to a data acquisition system (DAS) for subsequent processing. This data reveals information about the effects of the impact on the crash test dummy and can be correlated to the effects a similar impact would have on a human occupant.
In order to obtain more accurate test data, test engineers attempt to maximize what is known as the “biofidelity” of the crash test dummy. Biofidelity is a measure of how well the crash test dummy reacts like a human being in a vehicle impact test environment. A crash test dummy reacting as an actual human during a collision is said to have a high biofidelity. Accordingly, a crash test dummy having a high biofidelity will provide more accurate information from a collision test relative to the effect of the collision on a human being. Thus, ATD engineers design crash test dummies with the proper anthropometry that reflects a total weight, center of gravity, mass moment of inertia and range of motion similar to that of a human body so as to increase the biofidelity of the crash test dummy.
It is known to provide a neck for a crash test dummy. In one crash test dummy, the neck has a cylindrical design with grooves around the neck. A groove depth and angle are used to control a performance of the neck. While this neck provides good flexion and rear extension performance, it lacks the ability to adjust a lateral performance. In another crash test dummy, the neck has good lateral performance, but its flexion and extension performance were not so good and cannot be adjusted easily due to its axial symmetrical mechanical design.
From a biomechanics research study, a human neck has different performance in forward flexion and lateral bending. The bending stiffness are similar between the two directions up to a certain angles, where the frontal and lateral bending start to differentiate each other. For example, a 5th percentile female neck performance is shown in FIGS. 2 and 3. The slopes of the biofidelity response curves are approximately 0.58 in both directions (approximated in the thin dotted line in FIG. 3). However, when forward flexion reaches eighty degrees (80°) bending, the neck bottoms out and the stiffness increases quickly (approximated in the thin dotted line in FIG. 2). For lateral bending, the neck bottoms out near fifty degrees (50°).
Thus, it has been difficult to replicate a human neck for a crash test dummy. In particular, a neck was needed to be developed to be unique for frontal impact dummies or side impact dummies due to different responses in each direction. As a result, it is desirable to develop a neck for a crash test dummy that can perform like a human neck in both frontal and lateral bending directions. Therefore, there is a need in the art to provide a neck assembly for use in a crash test dummy so that biofidelity of the crash test dummy is improved.